I've tried to find a simple explanation to this and I'm really struggling.

Is it possible to push leads from one system into Marketo using API's? For example, an internal system (a like a custom built CRM) houses all the lead information but I want to get all this information in Marketo especially when data changes so that I can trigger email sends etc.

We have a custom CRM as well and use Marketo's API to push leads into the Marketo database. So yes, it's possible, but getting everything set up wasn't a simple switch that we just turned on. Do you have specific questions we can help with?

Do you have a dev team helping you or is this a marketing ops initiative?